diff --git a/tools/check b/tools/check
index e750ec7633a97f41d1e3c440b2bc1f5d149f882a..5457d73910a65ded713ad7ff3599396928c6ecba 100755
--- a/tools/check
+++ b/tools/check
@@ -1,6 +1,213 @@
-#!/usr/bin/env bash
+#!/usr/bin/python
+#
+# Software Carpentry Lesson Validator
+#
+# Check for errors in lessons built using the Software Carpentry template
+# found at http://github.com/swcarpentry/lesson-template.
+#
+# Usage:
+#
+# $ tools/check
-# Placeholder for actual conformance checking script (which will
-# probably be Python, not Bash).
+import sys
+import os
+import re
+import yaml
-grep -i -n 'FIX''ME' $*
+#----------------------------------------
+# Error reporting.
+
+def report_error(file_path, line_number, line, error_message):
+ """
+ Print information about general error.
+ """
+ ERR_MSG = "Error at line {} of {}:\n\t{}\n{}"
+ print(ERR_MSG.format(line_number, file_path, line, error_message))
+
+def report_missing(present, file_path, missing_element):
+ """
+ Print information about missing element.
+ """
+ ERR_MSG = "Error on {}: missing {}"
+ if not present:
+ print(ERR_MSG.format(file_path, missing_element))
+
+def report_missing_metadata(missing_element):
+ """
+ Print information about missing metadata at YAML header.
+ """
+ ERR_MSG = "Error on YAML header: missing {}"
+ print(ERR_MSG.format(missing_element))
+
+def report_broken_link(file_path, line_number, link):
+ """
+ Print information about broken link.
+ """
+ ERR_MSG = "Broken link at line {} of {}:\n\tCan't find {}."
+ print(ERR_MSG.format(line_number, file_path, link))
+
+#----------------------------------------
+# Checking.
+
+def check_yaml(metadata):
+ """
+ Check if all metadata are present at YAML header.
+ """
+ METADATA_REQUIRED = {"layout", "title", "minutes"}
+ for key in METADATA_REQUIRED - set(metadata.keys()):
+ report_missing_metadata(key)
+
+# TODO: Implement check_lesson
+def check_lesson(file_path):
+ """
+ Checks the file ``pages/[0-9]{2}-.*.md`` for:
+
+ - "layout: topic" in YAML header
+ - "title" as keyword in YAML header
+ - line "> ## Learning Objectives {.objectives}" after YAML header
+ - items in learning objectives begin with "*"
+ - items in learning objective following four-space indentation rule
+ - code samples be of type input, error, output, python, shell, r, matlab, or sql
+ - callout box style
+ - challenge box style
+ """
+ pass
+
+# TODO: Implement check_discussion
+def check_discussion(file_path):
+ """
+ Checks the file ``pages/discussion.md`` for:
+
+ FIXME: tell what need to check.
+ """
+ pass
+
+# TODO: Complete implementation of check_index
+# TODO: break check_index into pieces -- it's too long.
+def check_index(file_path):
+ """
+ Checks the file ``pages/index.md`` for:
+
+ - "layout: lesson" in YAML header
+ - "title" as keyword in YAML header
+ - introductory paragraph(s) right after YAML header
+ - line with "> ## Prerequisites"
+ - non-empty prerequisites
+ - title line with "## Topics"
+ - items at topic list begin with "*"
+ - items in topic list follow four-space indentation rule
+ - links at topic list are valid
+ - line with "## Other Resources"
+ - items at other resources list begin with "*"
+ - link at other resources list are valid
+ """
+ # State variables
+ in_yaml = False
+ yaml_metadata = []
+ has_prerequisites = False
+ has_topics = False
+ has_other_resources = False
+
+ # Load file and process it
+ with open(file_path, "r") as lines:
+ for line_number, line in enumerate(lines):
+ if re.match("---", line): # what if there are multiple YAML blocks??
+ in_yaml = not in_yaml
+ elif in_yaml:
+ yaml_metadata.append(line)
+ elif re.match("> ## Prerequisites", line): # check this in the Markdown or in the generated HTML?
+ has_prerequisites = True
+ elif re.match("## Topics", line): # as above?
+ has_topics = True
+ elif re.match("## Other Resources", line): # as above
+ has_other_resources = True
+ else:
+ ## Push this check into another function - this one is getting too long.
+ # Check if local links are valid
+ matches = re.search("\[.*\]\((?P<link>.*)\)", line)
+ if matches and not matches.group("link").startswith("http"):
+ link = os.path.join(os.path.dirname(file_path), matches.group("link"))
+ if link.endswith(".html"):
+ link = link.replace("html", "md") # NO: what about "03-html-editing.html" ?
+ if not os.path.exists(link):
+ report_broken_link(file_path, line_number, link)
+
+ ## Again, this function is too long - break it into sub-functions.
+ # Check YAML
+ yaml_metadata = yaml.load("\n".join(yaml_metadata))
+ check_yaml(yaml_metadata)
+
+ # Check sections
+ ## Note the refactoring: replaces three conditionals with one.
+ report_missing(has_prerequisites, file_path, "Prerequisites")
+ report_missing(has_topics, file_path, "Topics")
+ report_missing(has_other_resources, file_path, "Other Resources")
+
+# TODO Implement check_intructors
+def check_intructors(file_path):
+ """
+ Checks the file ``pages/instructors.md`` for:
+
+ - "title: Instructor"s Guide" in YAML header
+ - line with "## Overall"
+ - line with "## General Points"
+ - lines with topics titles begin with "## "
+ - points begin with "*" and following four space rules.
+ """
+ pass
+
+# TODO Implement check_motivation
+def check_motivation(file_path):
+ """
+ Checks the file ``pages/motivation.md``.
+
+ FIXME: tell what need to check.
+ """
+ pass
+
+# TODO Implement check_reference
+def check_reference(file_path):
+ """
+ Checks the file ``pages/reference.md`` for:
+
+ - ``layout: reference`` in YAML header
+ - line with "## Glossary"
+ - words definitions after at the "Glossary" as::
+
+ > **Key Word 1**: the definition
+ > relevant to the lesson.
+ """
+ pass
+
+def check_file(file_path):
+ """
+ Call the correctly check function based on the name of the file.
+ """
+ # Pair of regex and function to call
+ CONTROL = (
+ ("[0-9]{2}-.*", check_lesson),
+ ("discussion", check_discussion),
+ ("index", check_index),
+ ("instructors", check_intructors),
+ ("motivation", check_motivation),
+ ("reference", check_reference)
+ )
+ for (pattern, checker) in CONTROL:
+ if re.search(pattern, file_path):
+ checker(file_path)
+
+def main(list_of_files):
+ """
+ Call the check function for every file in ``list_of_files``.
+
+ If ``list_of_files`` is empty load all the files from ``pages`` directory.
+ """
+ if not list_of_files:
+ list_of_files = [os.path.join("pages", filename) for filename in os.listdir("pages")]
+
+ for filename in list_of_files:
+ if filename.endswith(".md"):
+ check_file(filename)
+
+if __name__ == "__main__":
+ main(sys.argv[1:])